My GATX cars arrived today, and they look great! They're due to go under the paintbrush soon for some light weathering. These Airglide cars became available in 1953, the same year I'm modeling, so I have to be careful not to go overboard. I'll probably give them a light dirt weathering with some moderate rust, especially around the hatches. I also read a how-to on adding spilled grain around the hatches using regular spices from the kitchen.
I'll post some progress pics when I get started!